1. Field of the Invention
The present invention relates to a photographing method and a photographing apparatus, which take a subject's image focused on an imaging surface through an imaging lens.
2. Description of the Related Art
Digital cameras, which detect an image representing a human face from taken images to automatically focus on the subject's face or to automatically change the zoom magnification so that the area representing the face in the detected image is enlarged, have been known (see Japanese Unexamined Patent Publication No. 2004-320286).
For use with such digital cameras, a method for automatically focusing on a subject's face, in which images for photographing conditions setting are taken when the shutter button is half pressed, and an image representing the face is detected from the images to focus on the face, has been known.
A digital camera using a “continuous face detection method” has been known. In the continuous face detection method, face detection for detecting an image representing a face from images taken for monitoring is constantly carried out even when the shutter button is not touched. Then, when a face is detected, the face is automatically focused. According to this method, the digital camera can be operated so that the face detection is always carried out and the detected subject's face is focused regardless of the operational state of the shutter button. Therefore, the display monitor can display images taken with the subject's face being always focused on, and photographing for recording an image (hereinafter may be referred to as “actual photographing”) can be carried out with no waiting time.
Further as a mechanism for focusing on the face, an AF (automatic focus) mechanism using a contrast detection method has been known. In the contrast detection AF mechanism, images are taken while the focusing lens group is moved within its operation range, and the image having the maximum contrast, i.e., having the maximum focus evaluation value, is found from the images. Then, the focusing lens group is set at the position where the image with the maximum contrast has obtained (see Japanese Unexamined Patent Publication No. 2004-320286).
Since a large amount of image processing is carried out in the above-described face detection operation, power consumption by the face detection operation is also large in proportion to the amount of processing. Frequent use of the face detection will result in early depletion of the battery power for driving the digital camera. Therefore, there are demands for reduction of power consumption by the face detection operation.
The face detected in the face detection operation is photographed (actual photographing) and recorded in a memory or the like. Thus recorded images may include unnecessary images containing a blurred face(s) due to, for example, movement of the hand holding the camera. Therefore, there are also demands for avoiding the face detection under conditions where unnecessary images will be photographed even with use of the face detection function, that is, under conditions where the face detection function is not efficiently used.